Influence of macro structure xylem on the density of pine and spruce xylem in mature virgin forest stands and spruce

The effect of plantation composition on the macrostructure and wood density of spruce and pine in stands with different proportions of participation of these species was studied. Wood samples for the study were taken at 44 stationary sites in mature spruce-pine stands of the bilberry group of forest types of the Leningrad region, unaffected by forestry impact during the period of growth. Quantitative data of measurements of early and late xylem zones, spruce and pine wood density were evaluated by statistical methods of processing – dispersion and rank analysis. A comparative analysis of the results depending on the share of spruce and pine in the stand composition was carried out. The study of the effect of plantation composition on xylem structure showed different dependence of xylem macrostructure of these tree species on the composition of the stand. As the proportion of spruce in the stand decreases, the relationship of early and late wood zones and its density with the composition of the stand increases. For the pine part of the stand, the parameters of the early wood zone and the width of annual growth tend to depend more on the composition of the stand with a decrease in its participation. Significant differences in the proportion of late wood in annual growth decrease with an increase in the share of pine in the composition of the stand. For spruce, it was found that with a decrease in its participation in the mixed stand, the relationship of macrostructure indicators with wood density is closer. The results of the study showed that pine wood density correlates closely with the macrostructural anatomical parameters of xylem - the width of the late and early wood zones.